1. Field of the Invention
The invention relates to a vehicle location estimation apparatus which estimates whether another vehicle in the periphery of a host vehicle is traveling on the same course as the host vehicle.
2. Description of Related Art
Technology is available in which information about other vehicles is acquired using vehicle-to-vehicle communications, and this information about other vehicles is used to assist driving in various ways, and so on. Since vehicle-to-vehicle communications are not yet widely used, it is necessary to ascertain with which other vehicle vehicle-to-vehicle communications are being conducted. Of the other vehicles with which vehicle-to-vehicle communications are being conducted, other vehicles traveling in the same direction on the same road (lane) as the host vehicle are especially important, and it is necessary to determine if these other vehicles are on the same course. Japanese Patent Application Publication No. 2005-115637 (JP 2005-115637A) discloses mapping locations indicated by forward vehicle information acquired from a radar, and forward vehicle information acquired from a vehicle-to-vehicle communications apparatus, to a mapping region established with reference to a host vehicle. The Japanese Patent Application Publication No. 2005-115637 also discloses identifying, from among the mapped vehicle locations, a vehicle location, which is closer than a prescribed distance and which has a high degree of matching in respect of the direction of travel, as a position of another vehicle existing in the vicinity of a host vehicle. Furthermore, Japanese Patent Application Publication No. 2010-146177 (JP 2010-146177A) and Japanese Patent Application Publication No. 2007-95038 (JP 2007-95038A) disclose using the travel trajectory of another vehicle conducting vehicle-to-vehicle communications to determine whether or not the other vehicle is on the same course.
Conventionally, in order to determine whether or not another vehicle is on the same course as the host vehicle, a highly accurate other vehicle location and map have been required, and the trajectory already travelled by the other vehicle has also been required. In particular, in the case of a map, preparing the road data is a huge burden and involves problems such as delays in updating the data, and so on. Furthermore, when the location of the other vehicle is mapped with reference to the host vehicle, as disclosed in JP 2005-115637A, then since that map is created on an experimental and empirical basis, it is very difficult indeed to adapt the map when there is a change in the travel scenario, installed sensors, and the like. Therefore, it has not been possible to determine whether or not the other vehicle is traveling on the same course, using simple equipment.